Continuous replenishment of electrodes in electric salt bath structures



March 8, 1949. R. c. UPTON CONTINUOUS REPLENISHMENT OF ELECTRODES INELECTRIC SALT BATH STRUCTURES 2 SheetsSheet 2 Filed Oct. 10, 1945 FIG.2.

INVENTOR.

RICHARD C.UPTON Flea.

ATTORNEYS Patented Mar. 8, 1949 am er CONTINUOUS BgRLENISHMl-INT OFELEC- TRODES IN EL C'I'RIC SALT BATH STRUC- TUBES Richard 0. Upton, hasClemens, Micln, as-

Ilgnor of one-half ..to Commerce Pattern Foundry. & Machine Company,Detroit,

Mich,

a corporation of Michigan Application October 10, 1945, Serial No.821,462

sou h...

The invention relates to electrically heated molten bath furnaces andthe method of operating the same.

It is the primary object of the invention to obtain a method forrepairing partially wastedelec;

trodes without interruption of the continuous use of the furnace.

It is a further object to automatically remove oxides from the bathduring continued operation of the furnace. With these and other objectsin view the invention consists in the construction and method ofoperation as hereinafter set forth.

In the drawings:

Fig. i is a plan view of the furnace;

Fig. 2 is a vertical section online 2-4, Fig. 1:

Fig. 3 is a cross section on line 3-4, Fig. 1.

In the operation of electrically heated molten bath furnaces, it isdiillcult or impossible'to avoid the introduction of oxides into themolten bath.

These have a very detrimental effect both on the furnace in the wastingof the electrodes and upon the work in decarbonizing the same: Theseoxides are due to many causes among which are the surface contact of themolten bath with the oxygen of the atmosphere and the absorption ofoxides from the surface of the work and fixtures.

Where metallic electrodes are used as, for-instance, iron electrodes,these under the high temperature of the bath and the presence of oxideswill quite rapidly waste away and where built into the furnace cannot bereplaced without disassembling the same.

In view of conditions as above described, I have devised a method ofrepairing partially wasted metallic electrodes as follows. When thefurnace is originally built, the electrodes are set in the refractorymaterial so as to expose only a top surface thereof to the molten bath.The temperature .of this bath such, for instance, as 2300 F., is abovethe melting point of a high carbon ferrous metal, such as cast iron, butis below the melting point of low carbonsteels. Consequently, by placingcast iron or similar metal in the bath above the exposed surface of awasted electrode, such metal will melt to flow into intimate contactwith and fuse onto said surface. If, however, there are oxides presentin the bath. these will eventually reduce the carbon content with theresult that the molten metal will solidify and become an integral partof the electrode. Thus, by this method the electrodes may be repaired asfrequently as necessary and without interruption in the operation of thefurnace.

Oxides which are present in the molten bath 2 maybe removed by reducingthe same to the metallic state and heretofore carbon has been used forthis purpose. Carbon is, however, of lower specific gravity than themolten bath and would naturally float thereon so as to have burning contact with the air and only limited surface contact with the bath. If thecarbon is submerged, then oxides in contact therewith at bathtemperature will b e'reduced to the metallic state and if the mcltinapoint thereof is higher than the bath temperature. ametaliic scale willbe formed covering the carbonsurface. However, as the melting point offerrous and certain other metals is lowered by increase in carboncontent, it is ob- 15 vious that the reduced metal will be in a moltenstate at bath temperature as long as it is free to absorb carbon. I havemade use of this fact to simultaneously reduce the oxide content of thebath and to form molten metal for restoring the electrode, thepreferable construction being as follows. A is the refractory lining ofthe furnace which, as shown, is rectangular and has a bottom A and sidewalls A. bedded in the bottom A so as to expose only their uppersurfaces, these being slightly lower than the surface of said member A.This will leave a shallow well above each electrode. The side walls 13havethe lower portions B thereof rising flush with the outer surface ofeach elec- 9 trod but the upper portions 3* of these side walls areinwardly offset to overlap portions of the electrodes. There are alsoinward projections B at each of the corners for a purpose hereinafterdescribed. The lining A is set within an outer s5 cement wall C-and theelectrodes 13 extend out through this wall and are preferably watercooled at their outer ends as is usual. D are carbon rods which arplaced beneaththe projections B and are held thereby against upwardmovement 40 through the bath. They are also'arranged above theelectrodes to extend longitudinally thereof and are inclined (as shownin Fig. 3) due to the placing of the projections B higher on one sidethan the other. These projections are also preferably undercut to retainthe carbon rods from lateral displacement.

With the construction as above described, a molten bath such, forinstance, as one formed of barium chloride will be maintained byelectrically generated heat at the desired temperature, such as 2300 F.After the furnace has been in use for some time. oxides will be absorbedby the bath but these coming in contact with the carbon rods D will bereduced to the metallic state. Also, sufllcient carbon will be absorbedto lower the melt- The electrodes B are em-' ing point of the metalbelow the bath temperature. Thus, liquid metal on the surface of the rodD will flow down the same and will finally drop off into the well abovethe electrode B to fuse to the surface thereof. Here it will be out ofcontact with the carbon and the reaction of other oxides still in thebath will reduce its carbon content until solidification takes place.Such process will continue automatically until the carbon rod has beenlargely consumed after which it may be removed and a new rod substitutedtherefor.

What I claim as my invention is:

1. In the operation of electrically heated molten bath furnacescontaining metallic oxides in the bath thereof and having one or moremetallic electrodes, the step of placing within the bath a reducingagent for converting said oxides into metal having a fusing point lessthan bath temperature and in a position where the molten metal will flowinto contact with an electrode.

2. In the operation of electrically heated molten bath furnacescontaining oxides in the bath thereof and having one or more metallicelectrodes, the steps of placing adjacent to an electrode a metalsufficiently high in carbon content to melt at bath temperature and toflow into contact with the surface of said electrode and subsequentlyreducing by reaction of said oxide the carbon content of the moltenmetalto solidify the same.

3. In the operation of electrically heated molten bath furnacescontaining metallic oxides in the bath thereof and having one or moremetallic electrodes, the steps of submerging a carbon rod in the moltenbath in a position above an electrode to first reduce a portion of saidmetallic oxides by contact with the surface of said rod and to drop thesame in a molten state upon said electrode in fusing contact therewithwhereupon further reaction between said oxides and the molten metal willreduce the carbon content of the latter and solidify the same.

4. In an electrically heated molten bath furnace, a refractorycontainer, a molten bath in said container and containing oxides, ametallic electrode, and a carbon rod submerged in said bath and arrangeddirectly above said electrode whereby said metallic oxides contactingwith said rod will be reduced into molten metal which is dropped fromsaid rod on said electrode.

5. In an electrically heated molten bath furnace, a refractorycontainer, an electrode located within a recess in the bottom of saidcontainer, a molten bath within said container and having oxidestherein, and metal having a sufficient carbon content to melt at bathtemperature and so located within said container as to flow the moltenmetal into said recess in fusing contact with said electrode wherebysaid oxides will reduce the carbon content of said metal to solidify thesame.

6. In an electrically heated molten bath furnace, a refractory containerhaving a recess in the bottom thereof, a metallic electrode locatedwithin said recess below the top thereof, a molten bath within saidcontainer and having metallic oxides therein, a carbon rod, and meansfor submerging said carbon rod in said bath above said electrode andrecess whereby a portion of said metallic oxides will be reduced bycontact with said carbon rod and the molten metal resulting therefromwill drop into said recess in contact with said electrode.

7. In an electrically heated molten bath furnace, a refractory containerfor the molten bath having a side wall undecut in its lower portion, abottom having a. recess therein which extends partly beneath saidundercut side wall, a metallic electrode in said recess, a molten bathin said container and containing metallic oxides, a carbon rod, ledgeson said side wall for holding said carbon rod submerged in the moltenbath above said recess and electrode and in an inclined position wherebya portion of the oxides in said bath will be reduced by contact withsaid carbon rod and the molten metal resulting therefrom will drain offsaid inclined rod into said recess in contact with said electrode.

8. In an electrically heated molten bath furnace, a refractorycontainer, a molten bath in said container containing metallic oxides, ame tallic electrode, and a reducing agent located in said bath abovesaid electrode for converting said oxides into metal having a fusingpoint less than the bath temperature and depositing the molten metal onsaid electrode.

RICHARD C. UPTON.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 971,782 Peterson Oct. 4, 19101,069,255 Heroult Aug. 5, 1913 1,373,615 Jacobs Apr. 5, 1921 1,875,787Wennerstrom Sept. 6, 1932 2,104,530 Sell Jan. 4, 1938 2,248,628 HopkinsJuly 8, 1941 2,349,678 Rolnick May 23, 1944 2,355,761 Upton Aug. 15,1944

